Number of Students with 2 Pets

In a class of 20 students, the teacher asked how many pets each student had. The results are shown in the bar graph below:

The number of students who have:

• 1 pet: 4 students
• 2 pets: 8 students
• 3 pets: 5 students
• 4 pets: 3 students

How many students have 2 pets?